Milestone 4: Complete frontend with: - Types aligned with backend schema - API client for CRUD operations - React Query hooks with optimistic updates - OwnershipCostForm with all 6 cost types - OwnershipCostsList with edit/delete actions - Mobile-friendly (44px touch targets) - Full dark mode support 🤖 Generated with [Claude Code](https://claude.com/claude-code) Co-Authored-By: Claude Opus 4.5 <noreply@anthropic.com>